Acrylic compositions are widely known and used as adhesives in the field of pressure sensitive and heat sensitive adhesives as shown by the following patents: U.S. Pat. Nos. 4,182,644 to Paul C. Briggs, Jr., 3,890,407 to Paul C. Briggs, Jr., 3,616,040 and 3,591,438 or 3,890,407 to Alex S. Toback. U.S. Pat. No. 4,602,073 prepares a two-part acrylic adhesive. Likewise, U.S. Pat. No. 4,600,738 teaches methods of making a two-component acrylic modified polyester adhesive. Unfortunately, these pressure sensitive adhesives are known for their relatively poor initial tackiness and much work has been directed to improving the initial tackiness.
The above enumerated U.S. patents are incorporated herein to disclose how to make pressure sensitive adhesives, hot melt adhesives and other adhesives. As used herein, the term "pressure sensitive adhesive" means the adhesive is tacky at ambient temperature whereas a "hot melt adhesive" is dependent upon temperature elevation, wherein the adhesive becomes tacky only upon temperature elevation.
In the past, many different organic silicones have been added to the acrylic pressure sensitive composition, or copolymers of silicones and acrylics have been made. For instance, Martin M. Sackoff et al. in U.S. Pat. No. 4,151,319 teach the making of a pressure sensitive adhesive by using blends of acrylics and silicones having poly(alkylene oxy)radicals. The data in Sackoff et al.'s Table 1 for peel values at zero and 20 minutes and longer times as well as the face-to-face peel data indicate the silicone acts as an unreactive filler and correspondingly lowers the initial tackiness relative to an all-acrylic pressure sensitive adhesive. Similarly, the Laurent Pat. No. 4,346,189 teaches the addition of 5 percent or 6 percent of polydimethylsiloxane, wherein the initial tack is not improved, but slitting is easier as the cutting blade or knife does not stick due to silicone release properties.